The present invention relates generally to industrial pressure measurement devices. In particular, the present invention relates to pressure measurement devices that include a capacitive pressure sensor.
Industrial pressure measurement devices, such as transmitters and pressure sensing modules, can be made either with or without embedded microprocessors. Transmitters that include embedded microprocessors typically have remote adjustment capabilities and have higher accuracies, higher linearity and higher costs. Transmitters built using analog or digital circuitry and without an embedded microprocessor usually have lower accuracies, lower linearity and lower costs. Modifications to improve the accuracy and linearity of transmitters by adding complex analog or digital circuitry but without adding embedded microprocessors can result in increased costs, decreased speed, or both.
There is a need to provide a pressure measurement device that can provide improved linearity and accuracy without the added cost of an embedded microprocessor or complex circuitry.
Disclosed is a pressure measurement device for sensing pressure. The pressure measurement device includes a digital clock circuit that provides an excitation clock and a control output. The pressure measurement device also includes a first integrator.
The first integrator includes a first switch controlled by the control output, a first amplifier, and a capacitive pressure transducer. The capacitive pressure transducer is fluidly couplable to an industrial process. The capacitive pressure transducer has a first pressure sensing capacitance that is electrically coupled in an amplifier feedback path between a first amplifier output and a first amplifier input. The first switch connects across the first pressure sensing capacitance. The first amplifier output represents the pressure.
The pressure measurement device includes a first reference capacitance that is insensitive to the pressure and that couples between the excitation clock and the first amplifier input.
These and various other features as well as advantages that characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.